﻿// Copyright 2013 rubicon informationstechnologie gmbh
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using InjectionCop.Parser;
using Microsoft.FxCop.Sdk;

namespace InjectionCop.Utilities
{
  public class ParameterFragmentUtility
  {
    public static Fragment ParameterFragmentIntersection (MethodCall methodCall, ISymbolTable context)
    {
      Fragment current = context.InferFragmentType (methodCall.Operands[0]);
      Fragment intersection = current;
      for (int i = 1; i < methodCall.Operands.Count; i++)
      {
        Fragment next = context.InferFragmentType (methodCall.Operands[i]);
        intersection = FragmentIntersection (current, next);
      }
      return intersection;
    }

    private static Fragment FragmentIntersection (Fragment fragmentA, Fragment fragmentB)
    {
      bool fragmentAIsSuperior = fragmentA != fragmentB && fragmentA == Fragment.CreateLiteral();
      bool fragmentBIsSuperior = fragmentA != fragmentB && fragmentB == Fragment.CreateLiteral();
      
      if (fragmentA == fragmentB)
        return fragmentA;
      else if (fragmentAIsSuperior)
        return fragmentB;
      else if (fragmentBIsSuperior)
        return fragmentA;
      else
        return Fragment.CreateEmpty();
    }
  }
}
